<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body,html {
            height: 100%;
            padding: 0;
            margin: 0;
        }
        .header,.footer {
            height: 40px;
            background: red;
        }
        .container {
            position: relative;
            height: calc(100% - 80px);
            padding: 0 200px;
        }
        .container > div {
            float: left;
        }
        .container:after {
            content: "";
            display: block;
            clear: both;
        }
        .left {
            position: absolute;
            left: 0;
            width: 200px;
            height: 100%;
            background: #2D64FA;
        }
        .middle {
            height: 100%;
            width: 100%;
            background: cyan;
        }
        .right {
            position: absolute;
            right: 0;
            width: 200px;
            height: 100%;
            background: #2D64FA;
        }
    </style>
</head>
<body>
    <div class="header">头部</div>
    <div class="container">
        <div class="left">1</div>
        <div class="middle">
            Lorem ipsum dolor sit amet, consectetur adipisicing elit. Laudantium obcaecati officiis provident quisquam temporibus! A commodi corporis, eius ex exercitationem harum ipsa ipsam iusto maiores modi repudiandae, totam voluptatem, voluptatibus.
        </div>
        <div class="right">3</div>
    </div>
    <div class="footer">底部</div>
</body>
</html>
